Changes in genetic and environmental influences on disordered eating between early and late adolescence: a longitudinal twin study

Two identical twin pairs discordant for longstanding anorexia nervosa and OSFED: lived experience accounts of eating disorder and recovery processes

Research into the risk of anorexia nervosa (AN) has examined twin pairs to further the understanding of the contributions of genetics, trait inheritance, and environmental factors to eating disorder (ED) development. Investigations of twin experiences of EDs have been biologically-based and have not considered the qualitative, phenomenological aspects of twin experiences. A gap in the literature exists regarding understanding of discordant twins with EDs. This research was developed in response, with the aim to deepen understanding of AN in discordant twins and to create novel ideas for further research and testing. The case studies presented in this article provide lived experience insights of two identical discordant twin pairs: one twin pair discordant for longstanding AN and one twin pair discordant for 'atypical' AN (the twin with AN has recovered). The perspectives and experiences of each co-twin (one with AN and one without) explore a number of factors that may have contributed to twin discordance in these cases, and how each twin has responded to the impact of AN in their lives. Through use of first-person accounts in case study presentation, this article centres social justice values of lived experience leadership and involvement in research. This article aims to extend current knowledge and understanding of EDs in discordant twins, particularly regarding risk for ED development, ED duration, diagnosis and treatment, and recovery processes.

Shared Genetic Influences Between Loss-of-Control Eating and Body Mass Index in Adolescent Twins

OBJECTIVE

Pediatric loss-of-control (LOC) eating is associated with high BMI and predicts binge-eating disorder and obesity onset with age. Research on the etiology of this common comorbidity has not explored the potential for shared genetic risk. This study examined genetic and environmental influences on LOC eating and its shared influence with BMI.

METHOD

Participants were 499 monozygotic and 398 same-sex dizygotic twins (age = 17.38 years ± 0.67, BMIz = 0.03 ± 1.03, 54% female) from the Colorado Center for Antisocial Drug Dependence Study. LOC eating was assessed dichotomously. Self-reported height and weight were converted to BMIz. Univariate and bivariate twin models estimated genetic and environmental influences on LOC eating and BMIz.

RESULTS

More girls (21%) than boys (9%, p < 0.001) reported LOC eating. The phenotypic correlation with BMIz was 0.03 in girls and 0.18 in boys. Due to the nonsignificant phenotypic correlation in girls, bivariate twin models were fit in boys only. Across all models, the best-fitting model included genetic and unique environmental effects. Genetic factors accounted for 0.51 (95% CI: 0.23, 0.73) of the variance of LOC eating in girls and 0.54 (0.18, 0.90) in boys. The genetic correlation between LOC eating and BMIz in boys was 0.45 (0.15, 0.75).

DISCUSSION

Findings indicate moderate heritability of LOC eating in adolescence, while emphasizing the role of unique environmental factors. In boys, LOC eating and BMIz share a proportion of their genetic influences.

Predicting eating disorder and anxiety symptoms using disorder-specific and transdiagnostic polygenic scores for anorexia nervosa and obsessive-compulsive disorder

BACKGROUND

Clinical, epidemiological, and genetic findings support an overlap between eating disorders, obsessive-compulsive disorder (OCD), and anxiety symptoms. However, little research has examined the role of genetics in the expression of underlying phenotypes. We investigated whether the anorexia nervosa (AN), OCD, or AN/OCD transdiagnostic polygenic scores (PGS) predict eating disorder, OCD, and anxiety symptoms in a large developmental cohort in a sex-specific manner.

METHODS

Using summary statistics from Psychiatric Genomics Consortium AN and OCD genome-wide association studies, we conducted an AN/OCD transdiagnostic genome-wide association meta-analysis. We then calculated AN, OCD, and AN/OCD PGS in participants from the Avon Longitudinal Study of Parents and Children to predict eating disorder, OCD, and anxiety symptoms, stratified by sex (combined N = 3212-5369 per phenotype).

RESULTS

The PGS prediction of eating disorder, OCD, and anxiety phenotypes differed between sexes, although effect sizes were small. AN and AN/OCD PGS played a more prominent role in predicting eating disorder and anxiety risk than OCD PGS, especially in girls. AN/OCD PGS provided a small boost over AN PGS in the prediction of some anxiety symptoms. All three PGS predicted higher compulsive exercise across different developmental timepoints [β = 0.03 (s.e. = 0.01) for AN and AN/OCD PGS at age 14; β = 0.05 (s.e. = 0.02) for OCD PGS at age 16] in girls.

CONCLUSIONS

Compulsive exercise may have a transdiagnostic genetic etiology, and AN genetic risk may play a role in the presence of anxiety symptoms. Converging with prior twin literature, our results also suggest that some of the contribution of genetic risk may be sex-specific.

Associations Between Attention Deficit Hyperactivity Disorder Symptom Dimensions and Disordered Eating Symptoms in Adolescence: A Population-Based Twin Study

Although bivariate associations between attention-deficit/hyperactivity disorder (ADHD) and eating disorders in adolescent girls and boys have been previously identified, the mechanistic link underlying the symptom-level associations remains unclear. We evaluated shared genetic and environmental influences on ADHD symptoms and disordered eating in 819 female and 756 male twins from the Swedish TCHAD cohort using bivariate models. Common additive genetic and unique environmental effects accounted for majority of ADHD and disordered eating associations in a differential manner. For girls, the strongest genetic correlation was observed for cognitive/inattention problems-bulimia (0.54), with genetic factors accounting for 67% of the phenotypic correlation. For boys, the strongest genetic correlations were observed for conduct problems-bulimia and hyperactivity-bulimia (~ 0.54), accounting for 83% and 95% of the phenotypic correlation, respectively. As per our findings, the risk of comorbidity and shared genetics highlights the need for preventative measures and specialized treatment for ADHD and disordered eating in both sexes.

Exploring the possibility of parents' broad internalizing phenotype acting through passive gene-environment correlations on daughters' disordered eating

Twin studies demonstrate significant environmental influences and a lack of genetic effects on disordered eating before puberty in girls. However, genetic factors could act indirectly through passive gene-environment correlations (rGE; correlations between parents' genes and an environment shaped by those genes) that inflate environmental (but not genetic) estimates. The only study to explore passive rGE did not find significant effects, but the full range of parental phenotypes (e.g., internalizing symptoms) that could impact daughters' disordered eating was not examined. We addressed this gap by exploring whether parents' internalizing symptoms (e.g., anxiety, depressive symptoms) contribute to daughters' eating pathology through passive rGE. Participants were female twin pairs (aged 8-14 years; M = 10.44) in pre-early puberty and their biological parents (n = 279 families) from the Michigan State University Twin Registry. Nuclear twin family models explored passive rGE for parents' internalizing traits/symptoms and twins' overall eating disorder symptoms. No evidence for passive rGE was found. Instead, environmental factors that create similarities between co-twins (but not with their parents) and unique environmental factors were important. In pre-early puberty, genetic factors do not influence daughters' disordered eating, even indirectly through passive rGE. Future research should explore sibling-specific and unique environmental factors during this critical developmental period.

The Impact of Teasing and Bullying Victimization on Disordered Eating and Body Image Disturbance Among Adolescents: A Systematic Review

Adolescence is a developmental period in which disordered eating and negative body image are highly prevalent, yet their risk factors are insufficiently understood and targeted. Despite research implicating both teasing and bullying victimization in the development of eating disorders, these strands of research are yet to be integrated. This systematic review hence aimed to identify whether teasing and bullying victimization are associated with greater risk of eating disorders and body image disturbance for adolescents. Systematic searches of PsycINFO and PubMed databases identified 79 papers that included quantitative analyses of the relationship between weight-related or nonspecific teasing or bullying victimization and disordered eating or body image disturbance. Overall, studies indicated that adolescents who are teased or bullied are more likely to experience disordered eating and negative body image compared to nonvictimized adolescents. This was more consistently observed in cross-sectional studies than in longitudinal findings. We identify several methodological limitations of the literature, including the infrequent consideration of potential mediating and moderating variables. Finally, we outline future directions such as temporal sequencing of the complex interrelationships among teasing and bullying, disordered eating, and body image disturbance in adolescents.

Potential eating disorder exhibited with daytime functional vulnerabilities associated with sleep problems in Japanese adolescents: A cross-sectional study

OBJECTIVES

Eating disorders (ED) are serious psychiatric disorders that affect individuals, especially adolescents. It has been suggested that nonclinical ED-like characteristics are related to sleep problems. We conducted a survey of Japanese adolescents to investigate this claim.

METHOD

In this cross-sectional study, 398 adolescents aged 12-18 years responded to a self-administered questionnaire survey. We used the Eating Attitudes Test-26 (EAT-26) and the Athens Insomnia Scale (AIS) to measure potential ED and sleep problems, respectively.

RESULTS

Adolescents with potential ED had significantly higher daytime functional vulnerability potentially associated with sleep problems than those without ED. In particular, problems with a sense of well-being and physical and mental functioning during the day were significant. In contrast, no significant associations were found between potential ED and sleep initiation, awakenings during the night, early morning awakening, total sleep duration, or overall quality of sleep. Finally, nocturnal and daytime sleep scores were significantly associated with dieting, bulimia, and oral control EAT-26 subscores.

DISCUSSION

Participants with possible ED experienced problems related to well-being and mental and physical functioning, which are indicators of daytime functional vulnerability potentially associated with sleep problems. Further, adolescents with more severe ED characteristics are more likely to have a higher degree of daytime psychological vulnerability potentially attributable to sleep problems. The study suggested that professionals treating adolescent mental health issues need an approach that comprehensively integrates both sleep problems and potential ED.

Can more people be "Happy Being Me"? Testing the delivery of a universal body satisfaction program by clinicians and school staff

The research presented here evaluates the delivery of Happy Being Me (HBM; Dunstan, Paxton & McLean, 2017) with boys and girls in their first year of secondary school in the UK (Year 7 and after comparisons aged 11-12). HBM is a manualised universal prevention programme which aims to improve body dissatisfaction and associated risk factors. Risk factors studied here were internalization of the thin ideal, physical appearance comparisons, appearance conversations. Secondary outcomes measured were self-esteem and eating disorder symptomsStudy 1 tested the effectiveness of HBM (n = 172) compared to a control group (n = 197) who received curriculum as usual. HBM resulted in significantly improved body satisfaction post-intervention which was maintained at follow up. There were no significant changes in risk factors.Study 2 compared clinician (n = 172) and teacher (n = 174) delivery. Students who received clinician-led, but not teacher-led, HBM had improved body satisfaction and this was maintained at follow up. Internalization of the thin ideal and self-esteem, improved in both clinician and teacher-led groups with small to medium sized effects. HBM can be delivered by clinicians independent of programme developers in a heterogeneous sample with positive effects on body satisfaction. Issues arising for wider delivery are discussed.

Peer victimization and weight/shape concerns in adolescents: Examining the moderating role of appearance-based rejection sensitivity

Peer victimization has been related to weight/shape concerns in adolescents. However, a dearth of research has examined potential moderators of this association. The present study examined the concurrent and prospective associations between two types of peer victimization, appearance-based and non-appearance-based, and weight/shape concerns among adolescents, and whether these associations were moderated by appearance-based rejection sensitivity. Participants were 897 adolescents, aged 11-19 years (M = 14 years 8 months, SD = 1 year 4 months), who completed a range of self-report measures as part of the EveryBODY study, one year apart. Both forms of victimization were associated with concurrent, but not prospective weight/shape concerns. Additionally, the concurrent association between appearance-related victimization and weight/shape concerns was dependent on appearance-based rejection-sensitivity, with stronger associations at lower levels of appearance-based rejection-sensitivity. These findings support previous research linking peer victimization with concurrent weight/shape concerns in adolescents. However, the impact of peer victimization on increased weight/shape concerns was not observed.

Sexual victimization and disordered eating among community individuals: The influence of negative and positive emotion dysregulation

OBJECTIVE

Individuals with a history of sexual victimization are at increased odds of developing an eating disorder in their lifetime. Emotion dysregulation has been identified as an outcome of sexual victimization and a vulnerability factor in the emergence and maintenance of disordered eating. However, research in this area has been limited by its narrow focus on dysregulation stemming from negative emotions. The aim of the current study was to explore the potential moderating roles of negative and positive emotion dysregulation in the relations between sexual victimization and disordered eating.

METHOD

Study participants included 473 community individuals who endorsed a history of sexual assault (M_age = 34.66; 44.8% male; 78.4% White). Participants completed measures assessing sexual victimization, negative and positive emotion dysregulation, and disordered eating. Data was collected from January to April of 2020 via Amazon's Mechanical Turk.

RESULTS

Results indicated significant positive relations among sexual victimization, negative and positive emotion dysregulation, and disordered eating. Sexual victimization was found to be more strongly associated with disordered eating at high (vs. low) levels of negative and positive emotion dysregulation.

DISCUSSION

This study provides evidence for the strengthening roles of both high negative and positive emotion dysregulation in the relation between sexual victimization and disordered eating, suggesting the potential utility of targeting both negative and positive emotion dysregulation in disordered eating interventions among individuals with a history of sexual victimization.

Seeing yourself clearly: Self-identification of a body image problem in adolescents with an eating disorder

AIM

Many adolescents who meet diagnostic criteria for an eating disorder do not self-identify as having a problem and may consequently be less likely to seek help. Extant research investigating self-identification has been limited to specific populations (ie, girls meeting criteria for bulimic-type eating disorders). This study investigated how self-identification varied across sex, eating disorder diagnoses, and the presence of extreme eating behaviours, and how self-identification was related to help-seeking in adolescents.

METHODS

Participants included 1002 Australian school students (75.5% female, M_age = 15.14 years, SD = 1.40) who met DSM-5 diagnostic criteria for an eating disorder. An online survey assessed self-identification of having a body image problem, as well as sex, eating disorder diagnosis, extreme eating behaviours, help-seeking for a body image problem, and other potential correlates of self-identification (demographics, psychological distress, social function, weight and shape concerns).

RESULTS

Approximately, 2 in 3 adolescents with an eating disorder self-identified as having a body image problem. Girls who met criteria for a major eating disorder diagnosis, and those engaging in extreme eating behaviours, were more likely to self-identify. When adjusting for covariates, only sex remained significantly associated with self-identification. Adolescents who self-identified were 2.71 times more likely to seek help for a body image problem, adjusting for covariates.

CONCLUSIONS

Public health strategies ought to promote awareness regarding the different ways that body image problems might manifest among both girls and boys, as well as the potential gravity of such problems. Awareness among parents, teachers and primary care providers should also be considered.

Common genetic architecture and environmental risk factors underpin the anxiety-disordered eating relationship: Findings from an adolescent twin cohort

OBJECTIVE

Despite established comorbidity between anxiety and disordered eating (DE), and a plethora of research using various methodologies to examine this overlap, use of twin modeling to expose whether a shared genetic liability underpins these conditions remains rare.

METHOD

Data from a longitudinal sample of female twins were selected: measures of risk for DE from Wave 1 (N = 699, 351 pairs, aged 12-15 years), and the Eating Disorder Examination (EDE) and Children's Anxiety Sensitivity Index (CASI) from Wave 2 (N = 669, 338 pairs, aged 16-19 years). At this time, they also completed Children's Anxiety Sensitivity Index (CASI). Bivariate Cholesky decomposition models adjusting for age and body mass index centile investigated the covariance structure between the CASI and EDE.

RESULTS

Modeling both genetic and nonshared environmental influences parsimoniously fit these data. All paths were significant. Additive genetic influences were notable for CASI and EDE phenotypes; 14% of the heritable variance was contributed by CASI to the expression of EDE. There was also a smaller but significant contribution of nonshared environmental influences. A multinomial logistic regression indicated body dissatisfaction (RRR = 1.53; 95% CI = 1.07-2.18) differentiated groups with highest EDE scores from the highest CASI scores.

DISCUSSION

Shared genetic and environmental influences appear to underpin the relationship, and potentially the observed comorbidity, between anxiety sensitivity and DE. The age of onset is typically earlier for anxiety than DE, suggesting a significant opportunity for early intervention work to reduce the likelihood of subsequent development of DE.

The Role of Puberty and Ovarian Hormones in the Genetic Diathesis of Eating Disorders in Females

Puberty is a critical risk period for eating disorders (EDs). ED incidence increases across the pubertal period and becomes female predominant, and genetic influences on disordered eating significantly increase. Surges of ovarian hormones, particularly estrogen, may drive this increasing genetic effect for EDs in pubertal girls and contribute to differential phenotypic presentations beyond puberty. In this article, we explain phenotypic associations between puberty and disordered eating and present evidence showing underlying genetic and hormonal influence. Potential benefits of communicating roles of genetic influence to people with or at risk for EDs are also discussed.

Etiological influences on continuity and co-occurrence of eating disorders symptoms across adolescence and emerging adulthood

OBJECTIVE

The role of common and symptom-specific genetic and environmental influences in maintaining eating disorder symptoms across development remains unclear. This study investigates the continuity and change of etiological influences on drive for thinness, bulimia, and body dissatisfaction symptoms and their co-occurrence, across adolescence and emerging adulthood.

METHOD

In total, 2,629 adolescent twins (mean age = 15.20, SD = 1.95) reported eating disorders symptoms across three waves of data collection. Biometric common pathways model was fitted to estimate genetic and environmental contributions to the continuity of each symptom over time, as well as time- and symptom-specific influences.

RESULTS

Drive for thinness and body dissatisfaction symptoms showed a pattern of high continuity across development and high correlations with each other, whereas bulimia symptoms were moderately stable and less associated with the other two symptoms. Latent factors reflecting continuity of each symptom were largely under genetic influence (A_l  = 0.60-0.82). New genetic influences contributing to change in the developmental course of symptoms were observed in emerging adulthood. Genetic influences correlated considerably between the three symptoms. Non-shared environmental influences were largely time-and symptom-specific, but some contributed moderately to the continuity across development (E_l  = 0.18-0.40). The etiological overlap was larger between drive for thinness and body dissatisfaction symptoms than with bulimia symptoms.

DISCUSSION

The results provide preliminary evidence that stable as well as newly emerging genetic influences contribute to the co-occurrence of drive for thinness, bulimia, and body dissatisfaction symptoms across adolescence and emerging adulthood. Conversely, environmental influences were less stable and contributed to change in symptoms over time.

Recent Research on Bulimia Nervosa

Estimates of lifetime bulimia nervosa (BN) range from 4% to 6.7% across studies. There has been a decrease in the presentation of BN in primary care but an increase in disordered eating not meeting full diagnostic criteria. Regardless of diagnostic status, disordered eating is associated with long-term significant impairment to both physical and mental quality of life, and BN is associated with a significantly higher likelihood of self-harm, suicide, and death. Assessment should adopt a motivationally enhancing stance given the high level of ambivalence associated with BN. Cognitive behavior therapy specific to eating disorders outperforms other active psychological comparisons.

Pediatric chronic patients at outpatient clinics: a study in a Latin American University Hospital

OBJECTIVE

To describe the characteristics of children and adolescentes with chronic diseases of outpatient clinics at a tertiary university hospital.

METHODS

A cross-sectional study was performed with 16,237 patients with chronic diseases followed-up in one year. The data were collected through the electronic system, according to the number of physician appointments in 23 pediatric specialties. Patients were divided in two groups: children (0-9 years) and adolescents (10-19 years). Early (10-14 years) and late (15-19 years) adolescent groups were also analyzed.

RESULTS

Of the total sample, 56% were children and 46% were adolescents. The frequencies of following pediatric specialties were significantly higher in adolescents when compared with children: cardiology, endocrinology, hematology, nephrology/renal transplantation, neurology, nutrology, oncology, palliative and pain care, psychiatry, and rheumatology (p<0.05). The frequencies of emergency service visits (30% vs. 17%, p<0.001), hospitalizations (23% vs. 11%, p<0.001), intensive care unit admissions (6% vs. 2%, p<0.001), and deaths (1% vs. 0.6%, p=0.002) were significantly lower in adolescents than in children. However, the number of physician appointments (≥13) per patient was also higher in the adolescent group (5% vs. 6%, p=0.018). Further analysis comparison between early and late adolescents revealed that the first group had significantly more physician appointments (35% vs. 32%, p=0.025), and required more than two pediatric specialties (22% vs. 21%, p=0.047). Likewise, the frequencies of emergency service visits (19% vs. 14%, p<0.001) and hospitalizations (12% vs. 10%, p=0.035) were higher in early adolescents.

CONCLUSIONS

This study evaluated a large population in a Latin American hospital and suggested that early adolescents with chronic diseases required many appointments, multiple specialties and hospital admissions.

Weighted Gene Co-Expression Network Analysis Reveals Dysregulation of Mitochondrial Oxidative Phosphorylation in Eating Disorders

The underlying mechanisms of eating disorders (EDs) are very complicated and still poorly understood. The pathogenesis of EDs may involve the interplay of multiple genes. To investigate the dysregulated gene pathways in EDs we analyzed gene expression profiling in dorsolateral prefrontal cortex (DLPFC) tissues from 15 EDs cases, including 3 with anorexia nervosa (AN), 7 with bulimia nervosa (BN), 2 AN-BN cases, 3 cases of EDs not otherwise specified, and 102 controls. We further used a weighted gene co-expression network analysis to construct a gene co-expression network and to detect functional modules of highly correlated genes. The functional enrichment analysis of genes in co-expression modules indicated that an altered mitochondrial oxidative phosphorylation process may be involved in the pathogenesis of EDs.

Shared familial risk between bulimic symptoms and alcohol involvement during adolescence

Twin studies show the established relation between bulimic symptoms and problematic alcohol involvement in adult females is partly due to shared familial factors, specifically shared genetic effects. However, it is unclear if similar shared etiological factors exist during adolescence or in males. We examined the familial overlap (i.e., genetic and common environmental correlations) between bulimic symptoms and various levels of alcohol involvement in 16- to 17-year-old female and male same-sex twin pairs using sex-specific biometrical twin modeling. Bulimic symptoms were assessed with the Eating Disorder Inventory-2. Alcohol involvement included alcohol use in the last month, having ever been intoxicated, and alcohol intoxication frequency. Results revealed 3 distinct patterns. First, in general, phenotypic correlations indicated statistically similar associations between bulimic symptoms and alcohol involvement in girls and boys. Second, common environmental overlap was significant for the bivariate associations including having ever been intoxicated. Third, moderate genetic correlations were observed between all bulimic symptoms and alcohol involvement in girls and moderate common environmental correlations were observed in boys for the more risky/deviant levels of involvement. Similar to adults, there is familial overlap between bulimic symptoms and alcohol involvement in adolescent girls and boys. These results could inform symptom- and sex-specific, developmentally targeted prevention and intervention programs for the comorbidity between bulimic symptoms and alcohol involvement. (PsycINFO Database Record

Weight-related peer-teasing moderates genetic and environmental risk and disordered eating: twin study

BackgroundWeight-related peer-teasing is considered a potent prospective risk factor for development of disordered eating and clinical eating disorders. Currently, the interplay between genetic and environmental influences has yet to be elucidated.AimsTo determine whether peer-teasing moderates latent genetic and/or environmental risk for disordered eating among female adolescent twins.MethodFull quantitative gene-environment interplay modelling of longitudinal trajectory of disordered eating in 685 female twins from the Australian Twin Registry.ResultsA model permitting moderation of disordered eating by peer-teasing involving genetic and non-shared environment effects fit these data best. As levels of peer-teasing increased, both genetic and environmental influences on disordered eating strengthened; however, genetic sources increased proportionally more than environmental sources.ConclusionsWeight-related peer-teasing represents a particularly powerful trigger for disordered eating. Nevertheless, it is amenable to intervention/prevention activities spanning individual to universal levels of endeavour.

Sex Differences in Binge Eating: Gonadal Hormone Effects Across Development

Eating disorders are highly sexually differentiated disorders that exhibit a female predominance in risk. Most theories focus on psychosocial explanations to the exclusion of biological/genetic influences. The purpose of this descriptive review is to evaluate evidence from animal and human studies in support of gonadal hormone effects on sex differences in binge eating. Although research is in its nascent stages, findings suggest that increased prenatal testosterone exposure in males appears to protect against binge eating. Although pubertal testosterone may exert additional protective effects, the prenatal period is likely critical for the decreased risk observed in males. By contrast, studies indicate that, in females, it is the lack of prenatal testosterone coupled with the organizational effects of pubertal ovarian hormones that may lead to increased binge eating. Finally, twin data suggest that changes in genetic risk may underlie these hormone influences on sex differences across development.

Prevention of eating disorders: A systematic review and meta-analysis

OBJECTIVE

To systematically review and quantify the effectiveness of Eating Disorder (ED) prevention interventions.

METHODS

Electronic databases (including the Cochrane Controlled Trial Register, MEDLINE, PsychInfo, EMBASE, and Scopus) were searched for published randomized controlled trials of ED prevention interventions from 2009 to 2015. Trials prior to 2009 were retrieved from prior reviews.

RESULTS

One hundred and twelve articles were included. Fifty-eight percent of trials had high risk of bias. Findings indicated small to moderate effect sizes on reduction of ED risk factors or symptoms which occurred up to three-year post-intervention. For universal prevention, media literacy (ML) interventions significantly reduced shape and weight concerns for both females (-0.69, confidence interval (CI): -1.17 to -0.22) and males (-0.32, 95% CI -0.57 to -0.07). For selective prevention, cognitive dissonance (CD) interventions were superior to control interventions in reducing ED symptoms (-0.32, 95% CI -0.52 to -0.13). Cognitive behavioural therapy (CBT) interventions had the largest effect size (-0.40, 95% CI -0.55 to -0.26) on dieting outcome at 9-month follow-up while the healthy weight intervention reduced ED risk factors and body mass index. No indicated prevention interventions were found to be effective in reducing ED risk factors.

CONCLUSIONS

There are a number of promising preventive interventions for ED risk factors including CD, CBT and ML. Whether these actually lower ED incidence is, however, uncertain. Combined ED and obesity prevention interventions require further research.

A systematic review and secondary data analysis of the interactions between the serotonin transporter 5-HTTLPR polymorphism and environmental and psychological factors in eating disorders

OBJECTIVES

To summarize and synthesize the growing gene x environment (GxE) research investigating the promoter region of the serotonin transporter gene (5-HTTLPR) in the eating disorders (ED) field, and overcome the common limitation of low sample size, by undertaking a systematic review followed by a secondary data meta-analysis of studies identified by the review.

METHOD

A systematic review of articles using PsycINFO, PubMed, and EMBASE was undertaken to identify studies investigating the interaction between 5-HTTLPR and an environmental or psychological factor, with an ED-related outcome variable. Seven studies were identified by the systematic review, with complete data sets of five community (n = 1750, 64.5% female) and two clinical (n = 426, 100% female) samples combined to perform four secondary-data analyses: 5-HTTLPR x Traumatic Life Events to predict ED status (n = 909), 5-HTTLPR x Sexual and Physical Abuse to predict bulimic symptoms (n = 1097), 5-HTTLPR x Depression to predict bulimic symptoms (n = 1256), and 5-HTTLPR x Impulsiveness to predict disordered eating (n = 1149).

RESULTS

Under a multiplicative model, the low function (s) allele of 5-HTTLPR interacted with traumatic life events and experiencing both sexual and physical abuse (but not only one) to predict increased likelihood of an ED and bulimic symptoms, respectively. However, under an additive model there was also an interaction between sexual and physical abuse considered independently and 5-HTTLPR, and no interaction with traumatic life events. No other GxE interactions were significant.

CONCLUSION

Early promising results should be followed-up with continued cross-institutional collaboration in order to achieve the large sample sizes necessary for genetic research.